swift234

Defer to the value witness when moving an archetype.  This
is really a deficiency in TypeInfo::initializeWithTake, which
is now virtual and not implemented in TypeInfo anymore.  This
fixes rdar://problem/12153619.

While I'm at it, fix an inefficiency in how we were handling
ignored results of generic calls, and add 4 new builtins:
  Builtin.strideof is like sizeof, but guarantees that it
  returns a multiple of the alignment (i.e., like C sizeof,
  it is the appropriate allocation size for members of an
  array).
  Builtin.destroy destroys something "in place";  previously
  this was being simulated by moving and ignoring the result.
  Builtin.allocRaw allocates raw, uninitialized memory, given
  a size and alignment.
  Builtin.deallocRaw deallocates a pointer allocated with
  Builtin.allocRaw;  it must be given the allocated size.

Swift SVN r2720